Special requirements - What do they mean?

Existing work authorization required: This means that candidates
are expected to have work authorization for the specific country where
the job is located. For example, if the job location is Mexico, "Existing
work authorization required" means the employer requires the candidate
to have already a work authorization in Mexico.

May consider sponsorship for work authorization: This means that
the employer may be able to sponsor the Work Authorization. For example,
if the job location is Mexico, "May consider sponsorship for work
authorization" means the employer may be willing to help you obtain a
work authorization in Mexico.